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Date:   Thu, 4 Apr 2019 21:52:10 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Nick Crews <ncrews@chromium.org>
Cc:     enric.balletbo@collabora.com, bleung@chromium.org,
        linux-leds@vger.kernel.org, jacek.anaszewski@gmail.com,
        alexandre.belloni@bootlin.com, a.zummo@towertech.it,
        linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org,
        dlaurie@chromium.org, sjg@google.com, groeck@google.com,
        dtor@google.com
Subject: Re: [PATCH v5 2/3] platform/chrome: Add Wilco EC keyboard backlight
 LEDs support
Message-ID: <20190404195210.GC29984@amd>
References: <20190404171007.160878-1-ncrews@chromium.org>
 <20190404171007.160878-2-ncrews@chromium.org>
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On Thu 2019-04-04 11:10:08, Nick Crews wrote:
> The EC is in charge of controlling the keyboard backlight on
> the Wilco platform. We expose a standard LED class device at
> /sys/class/leds/platform::kbd_backlight. This driver is modeled
> after the standard Chrome OS keyboard backlight driver at
> drivers/platform/chrome/cros_kbd_led_backlight.c
>=20
> Some Wilco devices do not support a keyboard backlight. This
> is checked via wilco_ec_keyboard_leds_exist() in the core driver,
> and a platform_device will only be registered by the core if
> a backlight is supported.
>=20
> After an EC reset the backlight could be in a non-PWM mode.
> Earlier in the boot sequence the BIOS should send a command to
> the EC to set the brightness, so things **should** be set up,
> but we double check in probe() as we query the initial brightness.
> If not set up, then set the brightness to 0.
>=20
> Since the EC will never change the backlight level of its own accord,
> we don't need to implement a brightness_get() method.
=2E..
> Signed-off-by: Nick Crews <ncrews@chromium.org>
> Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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